Can't remove door handle/lock for R&R
 

87 420 SEL (126) with a drivers door lock that wont turn. Since I can’t turn the key to remove the cylinder, I’ve got to remove the door lock to get the cylinder out. Got the door liner off, removed the 4 screws holding the door lock in place, removed the arm actuator and have the door handle screws removed. Manual says I have to be able to rotate the whole door handle for removal since I can’t rotate the key. Problem is I cant pull the handle mechanism out enough to rotate it. There is still something holding the whole thing is place. I see several pins that could be pushed out on the door handle for further disassembly of the door handle but they look like a PITA to put back in if I can’t move the door handle to my work bench. Some one else posted the problems he had mucking with the components accessible through the inside of the door, breaking a white plastic drum that I can clearly see. His post:
>>In order to disconnect the door handle I had to pry a small plastic drum which fit inside a keyhole to rotate, then release the lock/handle assembly. BOTH of these plastic pieces snapped off at this keyhole junction when carefully prying them up.<<
No one ever responded to him if he followed the proper procedure, so I’m not gonna mess with that just yet.

Any one know where I go from here? Its either start popping out some of those pins in the door handle or go in via the inside door panel and start breaking things!

I have the same problem on my 1983 300SD. The drivers lock does not really turn. It only turns a little bit and will sometimes get stuck. I'm going to remove the panel tomorrow to try and rehab the lock. Does anyone know how I can remove it if I am unable to turn the key in the lock and without damaging anything?